Sizing Guide Exchange Server 2003 - Fujitsu

White Paper Sizing Guide Exchange Server 2003 Version: 4.2, July 2006
A modern infrastructure based on Exchange Server 2003 will in comparison with an Exchange 5.5
environment consist of considerably less servers and above all fewer locations. Also in comparison with
Exchange 2000 Server a reduction in the locations is conceivable, because with the help of the cached
mode of Outlook 2003 and optimization of the communication between Outlook 2003 and Exchange Server
2003 a substantial reduction in the required network bandwidth is achieved.
Dedicated servers
In addition to e-mail, Exchange Server 2003 also offers a number of other components. It may therefore be
practical to distribute various tasks over dedicated Exchange servers. Thus a distinction is made between
the following Exchange server types:
The mailbox server - also frequently known as back-end server - houses the user mailboxes and is
responsible for delivering the mail to the clients by means of a series of different protocols, such as MAPI,
HTTP, IMAP4 or POP3.
The public folder server is dedicated to public folders, which are brought to the end user by means of
protocols, such as MAPI, HTTP, HTTP-DAV or IMAP4.
A connector server is responsible for various connections to other Exchange sites or mail systems. In
this regard, standard protocols, such as SMTP (Simple Mail Transfer Protocol), or X.400 can be used, or
proprietary connectors to mail systems, such as Lotus Notes or Novell GroupWise. Such a dedicated
server should then be used if a connection type is used very intensively.
The term front-end server is used for a server which talks to the clients and passes on the requests of
the client to a back-end-server, which typically houses the mailboxes and public folders. Such a
staggered scenario of front-end and back-end servers is frequently implemented for web-based client
accesses - Outlook Web Access (OWA).
Moreover, a distinction is made between so-called real-time collaboration servers, as well as data
conferencing servers, video conferencing servers, instant messaging servers and chat servers,
which accommodate one or more of these Exchange components in a dedicated manner. (Note: The
real-time collaboration features contained in Exchange 2000 Server have been removed from Exchange
Server 2003 and incorporated in a dedicated Microsoft product »Live Communications Server 2003« for
real-time communication and collaboration.)
Below, we will turn our attention to the most frequently used Exchange server type, the mailbox server, which
houses the users‟ mailboxes and public folders.
Active Directory and DNS
Exchange 2000 Server and Exchange Server 2003 is completely integrated into the Windows Active
Directory. Different to previous Exchange versions, such as 4.0 and 5.5, the information about mail users
and mail folders and is no longer integrated in Exchange, but is integrated in the Active Directory. Exchange
makes intensive use of the Active Directory and DNS (Domain Name System). This must be taken into
consideration with a complete design of an Exchange Server 2003 infrastructure, i.e. as well as Exchange
servers with adequate performance, Active Directory servers with an adequate performance are also
required, as this could otherwise have a detrimental effect on the Exchange performance. As Active
Directory typically mirrors the organizational structure of a company, organizational and geographical
realities must also be taken into consideration in the design. For performance reasons, apart from small
installations in the small business sector or branch offices, the Active Directory and Exchange may not be
installed on the same servers because the amount of processor and memory capacity required by an Active
Directory is substantial. Whereas the necessary disk storage is quite moderate for the Active Directory, a
substantial computing performance is required for the administration and processing of the accesses to the
Active Directory.
In larger Exchange environments the Exchange server should not simultaneously assume the role of a
domain controller, but dedicated domain controllers should be used. In this respect, the sizing of the domain
controllers is at least as complex as the sizing of Exchange servers. Since it would be fully beyond the scope
of this white paper, the topic of sizing the Active Directory cannot be discussed any further here. Helpful
information as to the design and the sizing of the Active Directory can be found at Windows Server 2003
Active Directory [L17].
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